This invention relates in general to a wheel mounting and, more particularly, to a wheel mounting having an axle-mounted sensor for measuring angular velocity.
An automotive vehicle that is equipped with an antilock braking system requires sensors to monitor the angular velocity of its individual wheels, so that when a wheel loses traction during the application of the brakes, the sensor at that wheel will detect a loss of velocity. The system actuates the brake at that wheel intermittently, thus enabling the vehicle to stop more efficiently and with better control. Traction control systems require sensors at the driven wheels to detect when one of the driven wheels loses traction and spins. The traction control system diverts the torque to the wheel which best exerts the tractive effort.
The typical sensor system for a vehicle has an excitor ring for each of the front wheels, and often for each of the rear wheels as well. Each excitor ring rotates with the road wheel with which it is identified. In addition, the system has a separate sensor for each excitor ring. Each sensor is mounted in a fixed position opposite its excitor ring with a small gap between the two. The sensor produces a signal which reflects the angular velocity of the excitor ring and the road wheel with which the ring rotates. The gap should remain within close tolerances and certainly should not exceed a prescribed dimension. It should also remain uniform during the operation of the bearing. Many sensor systems do not meet those requirements. Some manufacturers integrate the excitor rings and sensors into the bearings. Others fit the excitor rings to the wheel hubs and have the sensors mounted externally of the bearings. The former complicates the assembly of the bearings, whereas the latter complicates the installation of the hubs and renders the sensors vulnerable to displacement and damage.
One type of sensor system is installed on the axle which carries the wheel bearing, either with the installation of the bearing or prior to it. In any event, the carrier for the sensor and the bearing unite with a snap-type engagement, but this requires a modification of one of the bearing races.
The present invention resides in a wheel mounting including an axle, a hub located around a spindle on the axle, and an antifriction bearing located between the spindle and the hub. The axle also has an enlarged ring seat provided with a stop. The bearing has an inner race provided with a back face that is held firmly against the shoulder on the axle. The hub, on the other hand, carries an excitor ring which rotates with it. The ring seat on the axle carries a mounting ring which extends axially between the back face of the inner race and the stop along the seat. The mounting ring, in turn, carries a sensor which monitors the excitor ring, producing a signal which reflects the angular velocity of the excitor ring and hub. The invention also resides in a method of assembling the wheel mounting.